I know I can easily control this ultrasonic range sensor http://www.seeedstudio.com/wiki/index.php?title=Ultra_Sonic_range_measurement_module#Hardware_Installation directly with an Arduino,

but I was wondering whether there exists some sort of IC that would drive the sensor and convert its pulse output into an analog voltage output. So that the Arduino wouldn't have to switch pin mode and measure pulse width, but it would just read a voltage analog input continuously.

Sorry I misinterpreted the question. THis ping sensor gives a single pulse and its width is indicative for the distance.

Why not use an attiny13 - http://www.atmel.com/Images/doc2535.pdf - and send the value in a binary stream (SPI) to the Arduino.

There are other "minimal" processors that could do the job too..

Don't know much about the ATTiny - but could you instead output PWM and use a cap hanging off the pin to "output" an analog voltage level...? Main question would be if there are enough pins/resources to do that...

I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.